Electrical connector with shunt

ABSTRACT

An electrical connector having a shunt contact for short circuit interconnection of terminals in a housing, where during insertion of the terminal in the housing, the short circuit contact is biased away from the terminal by engagement of a housing locking lance thereagainst so that damage to the shunt contact is minimized, in particular reduced rubbing of the gold plated contact surface and reduced risk of buckling due to abutment of the contact mating end with the shunt during insertion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an electrical connector having a shunt orswitching contact.

2. Summary of the Prior Art

Provision of shunt or switching contacts in electrical connectors iscommon for a wide range of applications. Examples of connectors withshunt terminals are disclosed in DE 29 03 896, U.S. Pat. No. 4,850,888,U.S. Pat. No. 4,978,311 and EP 678 938. There are certain applicationswhere a particularly high reliability of the shunting contacts isrequired. For example, in automotive airbag or other safety systems,shunting contacts are provided for short circuiting the electrical leadsconnected to the detonator in order to prevent accidental ignition whenconnectors in the system are uncoupled (for example during maintenance).In applications where a particularly high reliability is required, it istypical to gold plate the contact surfaces between the shunting contactsand terminals. The adverse effects of corrosion deteriorating thecontact surfaces is thus avoided. The gold plating layer is usually verythin in order to reduce costs. Insertion or removal of terminals incavities of a connector housing may lead to damaging of the gold platedcontact surfaces as they rub against the shunt contact.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a shunt connector, withimproved reliability, in particular that reduces the risk of damage tocontact surfaces. It would be advantageous to provide a shunt connectorthat is particularly cost effective to manufacture and assemble.

Objects of this invention have been achieved by providing the connectoraccording to claim 1. Disclosed herein is an electrical connectorcomprising an insulative housing, a terminal mounted in the housing, anda shunt or switching contact mounted to the housing and engaging theterminal when fully assembled in the housing, the contact and terminalhaving respective contact surfaces that abut each other duringengagement, wherein the connector further comprises a projecting memberextending into a cavity of the housing for receiving the terminal, theprojecting member coupled to the shunt or switching contact duringinsertion of the terminal in the cavity such that the contact surface ofthe shunt or switching contact is biased away from the terminal. Rubbingof the shunt or switching contact with the terminal during insertion ofthe terminal in the housing is thus avoided. Removal and insertion ofthe terminal during repair is also not detrimental to the contactsurfaces.

The projecting member may be provided as a portion of the housing thatabuts and biases a portion of the shunt or switching contact duringinsertion of the terminal. The portion of the housing may be integrallyformed as a single part with the housing. In an advantageous embodiment,the projecting member could also act as a locking protrusion engagingbehind a locking shoulder of the terminal in the fully assembledposition, the locking protrusion being provided on a resilient lockingarm of the housing. For example the resilient locking lance of thehousing could be in the shape of a cantilever beam extending alongsidethe terminal receiving cavity from an attached end to a free end, wherethe free end engages the shunt contact.

It would also be conceivable to provide the projecting member as aseparate part moveable within the housing, or extending from the shuntor switching contact either integrally formed therewith, or overmouldedto the contact which may be a stamped and formed part from sheet metal.

In an advantageous embodiment, the contact may comprise a spring arm inthe form of a cantilever beam extending from an attachment portion to afree end being engaged by the projecting member during insertion of theterminal, for biasing the contact surface of the shunt away from theterminal.

Further advantageous aspects of this invention are described in theclaims, or will be apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through a connector according to thisinvention, during insertion of a terminal in a housing of the connector;

FIG. 2 is a view similar to that of FIG. 1 but with a fully insertedterminal;

FIG. 3 is a view similar to the FIGS. 1 and 2 without the terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, an electrical connector 2 comprises aninsulative housing 4 extending from a terminal receiving end 6 to amating end 8 with terminal receiving cavities 10 extending therethroughfor receiving terminals 12. The connector may comprise a plurality ofterminal receiving cavities 10 arranged in a row each for receiving aterminal. The connector may also be provided with a plurality of rows ofterminals stacked upon each other, however the invention can bedescribed with a single terminal and receiving cavity as shown in FIGS.1-3. The connector 2 further comprises a shunt contact 14 securelymounted to the housing 4. The shunt contact in this embodiment is forelectrically interconnecting two or more of the terminals 12, but theshunt contact 14 could also contact only a single terminal 12 of theconnector 2 if it functions as a switching contact where the shuntcontact is connected to a conductor external to the connector.

The terminal 12 comprises a connection section 16 for connection to aconductor such as a conducting wire, and a contact section 18 for matingwith a complementary terminal of a mating connector (not shown). Thecontact section 18 in the terminal of the present embodiment is a tab orpin terminal for mating with a receptacle terminal. The terminal 12 isprovided with retention means in the form of a locking shoulder 20provided in a cutout 22 of a body section 24 of the terminal, the bodysection 24 positioned intermediate the contact section and theconnection section. The terminal retention means 20 engages with acomplementary retention means of the housing 4, provided in the form ofa locking shoulder 26 on a locking projection 28 that projects throughthe terminal cutout 22 once the terminal is fully inserted in the cavity10 as shown in FIG. 2. The locking projection 28 is provided on aflexible lance 30 that is integrally formed with the housing 4. Thelance 30 extends from an attachment end 32 to a free end 34 positionedproximate an inner mating face 36 of the housing. The locking projection28 is positioned proximate the free end 34. The lance 30 is outwardlybiasable within a slot 36 of the housing, where biasing of the lanceoccurs during insertion of the terminal 12 in the cavity 10 by abutmentof the projection 28 against the terminal.

The shunt contact 14 comprises a base or mounting portion 38 and aspring arm 40 extending therefrom at an attachment end 42 to a free end44. The shunt contact comprises a contact protrusion 46 providing anarcuate contact surface for abutment against the terminal 12, positionedproximate the free end 44. The contact protrusion 46 s resilientlybiased towards the terminal by virtue of spring arm 40. The attachmentportion 42 comprises a U-shaped bend interconnecting the base portion tothe spring arm.

The shunt contact base portion 38 comprises retention means that may bein the form of locking projections, or barbs, or a resilient lockinglance, or simply an interference fit with a cavity 48 in the housing 4which receives the base portion 38. The base portion 38 thus serves tosecurely mount the shunt contact to the housing 4. The base portion 38may also comprise an extension such that the base portion extends acrosstwo or more terminals arranged in adjacent cavities for short circuitinterconnection of two or more terminals. For example a row of cavities10 may be provided in the housing, (the row extending in a directionperpendicular to the plane of the drawings in FIGS. 1-3) whereindependent spring arms 40 may be connected to the base portion 38, eachfor contacting a different terminal.

It is also conceivable to provide the base portion 38 with a connectionsection for connection to a conducting wire for example, where the shuntcontact connects only to one terminal and acts as a switching contact.

The shunt contact spring arm 40 extends within a cavity 50 adapted toreceive a portion of a mating connector therein, the mating connectorcomprising means for biasing the shunt contact to disconnect theterminal from the shunt contact, as is typical with shunting functionsin conventional connectors.

During insertion of the terminal 12 in the cavity 10, the shunt free end44 is biased out of contact with the terminal by projecting meansextending between the terminal and the shunt. In this embodiment, theprojecting means are provided on the locking lance 30, whereby the freeend 34 of the locking lance abuts against the free end 44 of the shuntcontact and the locking projection 28 cams over the body of the terminal12 as shown in FIG. 1. Upon full insertion of the terminal as shown inFIG. 2, the resilient lance 30 snaps into its locking position, therebyreleasing the shunt contact which biases against the terminal, (in thisembodiment the contact section 18 of the terminal). Rubbing of the shuntcontact surface is thus avoided, thereby reducing the risk of damage ofthe contact surface. The latter is particularly important where thecontact surface is gold plated (or plated with another anti-corrosionmaterial).

Another important advantage of the invention is to enable passage of theterminal past the contact protrusion 46, which may otherwise stub orabut against the mating end of the terminal and buckle or otherwisedamage the shunt contact. To avoid such problems in a conventionalconnector, a smooth and long tapered guiding portion extending from thefree end of the shunt arm is required, which consumes space. Anotheradvantage is to use the engagement of the projection means with theshunt contact for prestressing the shunt spring arm 40 as best shown inFIG. 3. The shunt spring arm 40 can thus be provided under stress byabutment of the free end 44 against the housing lance free end 34 suchthat a large contact force is provided during shunt interconnection asshown in FIG. 2.

In other embodiments, the projection member 30,34 may be provided on aseparate part with respect to the main portion of the housing 4 (i.e.not integrally connected as with the lance 30 of the present embodiment)and it may not be necessary to provide the locking function integrallytherewith, although the combination of the locking function and shuntseparation function is particularly simple and therefore also reliableand cost-effective. For example it would be possible to attach anextension to the shunt free end 44 that abuts against the terminal andacts as the projecting member that separates the shunt contact duringinsertion of the terminal, such projection also being received in arecess or cavity of the terminal. Such projection may be for exampleintegrally stamped and formed with the shunt contact, or provided as aplastic extension overmoulded over the free end 44.

We claim:
 1. An electrical connector comprising an insulative housing, aterminal mounted in the housing, and a shunt or switching contactmounted to the housing and having a contact surface engaging theterminal when the terminal is fully assembled in the housing, theconnector further comprises a projecting member extending into a cavityof the housing for receiving the terminal, the projecting member pushedby the terminal during insertion of the terminal in the cavity so thatthe projecting member is coupled to the contact such that the contactsurface is biased away from the terminal.
 2. The connector according toclaim 1 wherein the projecting member is part of the housing.
 3. Theconnector according to claim 2 wherein the projecting member comprises alocking protrusion having a locking shoulder engaging in a recess orcavity of the terminal defining a locking shoulder, for engagement withthe projecting member locking shoulder in order to retain the terminalin the housing.
 4. The according to claim 1 wherein the projectingmember is provided on a resilient lance.
 5. The connector according toclaim 4 wherein the resilient lance is integrally formed with thehousing.
 6. The connector according to claim 5 wherein the resilientlance is in the shape of a cantilever beam attached at an attachment endto the housing and extending therefrom alongside the terminal receivingcavity to a free end, the resilient lance engaging the shunt orswitching contact proximate the free end.
 7. The connector according toclaim 6 wherein the shunt or switching contact engages the projectingmember in a prestressed manner prior to insertion of terminal in thecavity.
 8. The connector according to claim 1 wherein the contactcomprises a spring arm extending from an attachment portion to a freeend, the attachment portion extending from a base portion received in acavity of the housing, the base portion being provided with retentionmeans for securely mounting the shunt to the housing.
 9. The connectoraccording to claim 8 wherein the contact is provided with a contactprotrusion for abutment against the terminal proximate the free end. 10.The connector according to claim 9 wherein the free end of the contactengages the projecting member.